The present invention relates generally to nonwoven fabrics and their method of production, and more particularly to a process for making stabilized, highly durable hydroentangled webs, comprising a blend of textile length fibers where a portion of same are thermally fusible, and where such fabrics are suitable for commercial dyeing operations, most particularly jet-dye processes.
Nonwoven fabrics are used in a wide variety of applications where the engineered qualities of the fabric can be advantageously employed. These types of fabrics differ from traditional woven or knitted fabrics in that the fabrics are produced directly from a fibrous mat eliminating the traditional textile manufacturing processes of multi-step yarn preparation, and weaving or knitting. Entanglement of the fibers or filaments of the fabric acts to provide the fabric with a substantial level of integrity. However, the required level of fabric integrity when such fabrics are used in highly abrasive environments is not possible by entanglement alone, and thus it is known to apply binder compositions or the like to the entangled fabrics for further enhancing the integrity of the structure.
U.S. Pat. No. 3,485,706, to Evans, hereby incorporated by reference, discloses processes for effecting the hydroentanglement of nonwoven fabrics. More recently, hydroentanglement techniques have been developed which impart images or patterns to the entangled fabric by effecting hydroentanglement on three-dimensional image transfer devices. Such three-dimensional image transfer devices are disclosed in U.S. Pat. No. 5,098,764, hereby incorporated by reference, with the use of such image transfer devices being desirable for providing fabrics with the desired physical properties as well as an aesthetically pleasing appearance.
In general, hydroentangled fabrics formed on the above type of three-dimensional image transfer devices exhibit sufficient strength and other requisite physical properties as to be suitable for a number of textile applications.
However, many desired applications have requirements for commercial dyeing and wash durability, which are generally beyond the design capability of such fabrics. Typically, home or commercial laundering or the rigors of commercial dye house processes have a deleterious effect on these hydroentangled or imaged fabrics. The clarity of the raised image is reduced or xe2x80x9cwashed outxe2x80x9d and the fabric surface becomes abraded with fibers forming pills on the fabric surface. Physical strength characteristics can also be reduced.
Heretofore, chemical binder systems have been developed that provide high abrasion resistance to nonwoven, woven or knitted fabrics. Other binder compositions can provide durability to laundering and commercial dyeing processes. However, it will be appreciated that application of chemical binders also increases the complexity of the fabric manufacturing process and adds cost to the fabric thus produced. The use of such compositions also requires specialized equipment to mix and apply the binder formulations as well as to dry and cure the binder compositions after application to the fabrics.
The addition of binder compositions has an effect on the fabric properties. The use of such binders generally produces fabrics which are stiffer than like fabrics produced without the binder application. Such stiffness will be recognized as being undesirable for apparel fabrics, where softness, suppleness and drapeability are highly preferred.
The present invention is directed to a process for making nonwoven fabrics which exhibit the desired durability to commercial dye house processing, most particularly jet-dye processing, as well as acceptable softness and drapeability. This is achieved by the inclusion of fusible fibers, preferably in the form of bicomponent fibers, most preferably nylon or polyester bicomponent fibers, into the fibrous matrix of the substrate web. Such fibers, when the entangled and patterned web is subjected to temperatures above the melting point of the lower melting component of the bicomponent fibers, acts to provide enhanced mechanical stability to the fibrous matrix of the web. An imaged nonwoven fabric with this added degree of mechanical stabilization has been found to be durable to commercial dye house processing, in particular to the mechanically aggressive jet-dye processing, and able to retain the imparted image quality under harsh mechanical conditions.
A process for making a jet-dye process-durable nonwoven fabric in accordance with the present invention comprises the steps of providing a fibrous matrix to form a precursor web comprised of a blend of textile length fibers where at least a portion of those fibers are bicomponent, thermoplastic fibers. The fibrous component of the precursor web can be in the form of a fibrous batt or matrix containing a single homogenous blend of fusible fibers or in a layered fibrous batt having either the same or different fusible fiber blend ratios in each fibrous batt sub-layer, with the matrices consolidated to form the precursor web. The precursor web is positioned on a three-dimensional image transfer device with hydroentangling of the precursor web on the image transfer device effected to form an entangled and imaged web, with the image transfer device imparting the fibrous matrix with a three-dimensional spatial arrangement.
Subsequent to the hydroentanglement and imaging of the web, the temperature of the web is elevated, such as during drying of the web, so that the lower melting point component of the bicomponent fusible fibers is softened or melted and acts to thermally bond fibers in the web together. The three-dimensional spatial arrangement of the fibrous matrix is thus secured. This results in an enhanced mechanical stability such that the highly durable fabric of the present invention is capable of being commercially dyed, without deleterious effects on aesthetic or physical properties. The commercial dye processing produces, as the final product, a colored, highly durable, imaged nonwoven fabric.
Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings and the appended claims.